Manual transmissions are used for various vehicle applications. Such transmissions typically include a multiple speed main section containing a plurality of gears for various range and load gearing configurations. Traditionally, a clutch provides momentary torque interrupt when gear ratio changes occur. The clutch is used to engage the transmission from a driving shaft powered by an engine. Shifting with torque interrupt, however, is a manually demanding process that requires repeated engagement of the driver.
Systems have been developed to improve the shifting process, such as automated manual transmissions (AMTs) and dual clutch transmissions (DCTs). An AMT includes a clutch, a gearbox, and an embedded dedicated control system that uses electronic sensors, processors, and actuators to actuate gear shifts on the driver's throttle pedal command. An AMT removes the need for a clutch pedal while the driver is still able to control vehicle movement. The clutch itself is actuated by electronic equipment that can synchronize the timing and the torque required to make gear shifts quick and smooth.
Dual clutch transmissions (DCTs) have been developed that enable shifting between sets of gears without torque interrupt. In a dual clutch, the inner shaft and the outer shaft may have two or more connectable gears (via sliding clutches or sliding clutches and synchronizers) that drive their respective downstream layshaft members for appropriate speed ratios. The clutches can be alternately engaged as the gear progression is achieved between, for example, four sequential gears to permit power shifting between the progressive four ratios.
In some transmission designs, the number of gear shift options results in the operator having to shift up sequentially through all gear ratios before reaching full speed. Such transmission designs can include either an AMT or a DCT. It is desirable to increase the number of gear ratios in the transmission to facilitate skip shifting in lower gears while having an adequate range of operation of the gears at higher speeds for improved fuel efficiency. However, in some configurations the layout of the transmission can result in an increased length of the input shaft extension from its support bearing, which can compound eccentricity problems due to the increased length.
Therefore, it is desirable to provide a transmission having an increased number of gear ratios available to skip shift in lower speeds and have an adequate range of operation at higher speeds.